Reflected light

matter where the ray reflects at the mirror. But the straight line (solid path) is the shortest distance from A to B* and therefore also the shortest path from A to B. For that path, and for that path only, the angle between the ray and the mirror is the same for the incident and reflected rays.

It is usual to define angles of incidence and reflection with respect to the normal (the line perpendicular to the surface at the point of reflection), as shown in Figure 2.3.

Law of reflection: The angle of incidence is equal to the angle of reflection. This is the first practical consequence of Fermat's law.